Send node transition events for touch events

third_party/WebKit/Source/core/input/PointerEventManager.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PointerEventManager_h
+#define PointerEventManager_h
+
+#include "core/CoreExport.h"
+#include "core/events/PointerEvent.h"
+#include "core/events/PointerEventFactory.h"
+#include "public/platform/WebInputEventResult.h"
+#include "public/platform/WebPointerProperties.h"
+#include "wtf/Allocator.h"
+#include "wtf/HashMap.h"
+
+namespace blink {
+
+/**
+  Helper class for tracking the pointer ids for each type of PointerEvents.
+  Using id re-mapping at this layer, this class makes sure that regardless of the
+  domain of the id (i.e. in touch or pen) the corresponding pointer event will have
+  a unique id amongst all pointer events as per pointer events' specification.
+  This class intended to behave the same as existing browsers as much as possible
+  for compatibility reasons. Particularly it behaves very similar to MS Edge to have
+  pointer event ids generated by mouse always equal 1 and those that are generated
+  by touch and pen will have increasing ids from 2.
+*/
+class CORE_EXPORT PointerEventManager {
+    DISALLOW_NEW();
+public:
+    PointerEventManager();
+    ~PointerEventManager();
+    DECLARE_TRACE();
+
+    WebInputEventResult sendMousePointerEvent(
+        PassRefPtrWillBeRawPtr<Node>, const AtomicString& type,
+        int clickCount, const PlatformMouseEvent&,
+        PassRefPtrWillBeRawPtr<Node> relatedTarget,
+        PassRefPtrWillBeRawPtr<AbstractView>);
+
+    // Returns whether the event is consumed or not
+    WebInputEventResult sendTouchPointerEvent(
+        PassRefPtrWillBeRawPtr<EventTarget>,
+        const PlatformTouchPoint&, PlatformEvent::Modifiers,
+        const double width, const double height,
+        const double clientX, const double clientY);
+
+    void sendTouchCancelPointerEvent(PassRefPtrWillBeRawPtr<EventTarget>,
+        const PlatformTouchPoint&);
+
+    // Sends node transition events (pointer|mouse)(out|leave|over|enter) to the corresponding targets
+    void sendNodeTransitionEvents(PassRefPtrWillBeRawPtr<Node> exitedNode,
+        PassRefPtrWillBeRawPtr<Node> enteredNode,
+        const PlatformMouseEvent&,
+        PassRefPtrWillBeRawPtr<AbstractView>);
+
+    // Clear all the existing ids.
+    void clear();
+
+    // Clear PREVENT MOUSE EVENT flag as per pointer event spec:
+    // https://w3c.github.io/pointerevents/#compatibility-mapping-with-mouse-events
+    void clearPreventMouseEventForPointerTypeMouse();
+
+private:
+    PassRefPtrWillBeRawPtr<Node> getEffectiveTargetForPointerEvent(
+        PassRefPtrWillBeRawPtr<Node>,
+        PassRefPtrWillBeRawPtr<PointerEvent>);
+    void sendNodeTransitionEvents(
+        PassRefPtrWillBeRawPtr<EventTarget> exitedTarget,
+        PassRefPtrWillBeRawPtr<EventTarget> enteredTarget,
+        PassRefPtrWillBeRawPtr<PointerEvent>,
+        const PlatformMouseEvent& = PlatformMouseEvent(),
+        bool sendMouseEvent = false);
+    void setNodeUnderPointer(PassRefPtrWillBeRawPtr<PointerEvent>,
+        PassRefPtrWillBeRawPtr<EventTarget>);
+
+    // Prevents firing mousedown, mousemove & mouseup in-between a canceled pointerdown and next pointerup/pointercancel.
+    // See "PREVENT MOUSE EVENT flag" in the spec:
+    //   https://w3c.github.io/pointerevents/#compatibility-mapping-with-mouse-events
+    bool m_preventMouseEventForPointerTypeMouse;
+
+    WillBeHeapHashMap<int, RefPtrWillBeMember<EventTarget>> m_nodeUnderPointer;

[mustaq, 2016/02/11 16:15:16]

This surely needs some attention. We can easily have:
  m_nodeUnderPointer.get(mouse) != EventHandler::m_nodeUnderMouse
for (legacy) mouse events that don't fire PEs.

What if we add {get,set}NodeUnderMouse() here to get rid of the state in
EventHandler?

[Navid Zolghadr, 2016/02/11 16:34:52]

I had that problem in mind. The catch is that this map is not yet handling mouse
events yet. It is only for touch events and it works for them just fine (i.e.
the setNodeUnderPointer is only called in touch functions). When I add the
tracking of mouse (and mouse like pen events) then I will need to clean up that
piece of code from EventHandler as well.

[mustaq, 2016/02/11 16:51:12]

Sorry didn't get it: for touch, we are currently sending mouse transition
events, right? Are we not updating m_nodeUnderMouse?

[Navid Zolghadr, 2016/02/11 17:47:49]

Not through PointerEventManager class. EventHandler takes care of those using
m_nodeUnderMouse. I will add a comment explaining this field for now.

+    PointerEventFactory m_pointerEventFactory;
+};
+
+} // namespace blink
+
+#endif // PointerEventManager_h